1. Field of the Invention
This invention relates to a bottle for reception and metered delivery of liquids, produced from plastic using injection molding techniques and having a cap.
2. Description of Prior Art
Various liquids are known, which are only required in small amounts, in addition are light-sensitive and have a high coefficient of diffusion and permeation, which are diffused easily. Decomposition products or oxidation can occur under the effects of light, while diffusion can alter the composition of the product. For example, the concentration of effective agents in a medicament can be increased to an alarming degree because of the evaporation of the solvent. In any case, the shelf life of the packaged goods is affected by the packaging.
Although glass containers are good barriers for diffusion, the impermeability to light can only be produced by expensive special glass. It is then necessary to employ pipettes for metering the contents, which are extremely expensive and have further problems regarding gas diffusion in the area of the bellows.
Accordingly, plastic bottles are therefore indicated as an alternative. Most of the plastics which can be used in injection molding or blowing technology do not have particularly high values regarding light impermeability and permeation and diffusion density. Because of the three permeation steps, namely absorption, diffusion and desorption, generally diffusion alone determines speed, only diffusion will be addressed in the following specification, however, without ruling out absorption and desorption. If methods of injection molding technology are used, it is possible to appropriately increase the wall thickness. However, in this case the container becomes rigid to such an extent that liquid can only be removed using a pipette.
A further alternative lies in blowing plastic bottles in several layers. Two-layered or three-layered bottles with appropriate blocking layers can thus be produced in this way. All of these have the same overall wall thickness. Such containers are relatively expensive and appropriate machines are required, which are only available at all in a few plastic-processing companies. Although the squeezable plastic bottles permit metering of the liquid, this is only possible with a very light touch. Since the wall thickness of blown containers is generally consistent, the container is deformed over the entire container wall when it is squeezed. This makes dispensing of small amounts more difficult.